1. Field of the Invention
One embodiment of the present invention relates to a memory device.
2. Description of the Related Art
In recent years, memory devices capable of rewriting data have been developed.
As an example of such memory devices, a content addressable memory can be given.
The content addressable memory is a memory device which can not only rewrite data but also compare search data with data stored in a memory cell.
The content addressable memory is used for a set-associative cache memory, for example. The set-associative structure is a data storage structure including a plurality of tags, and a content addressable memory is used as each of the tags. The use of the content addressable memory for the cache memory can increase the data communication speed between a CPU and the cache memory.
A memory cell in a content addressable memory includes, for example, a memory circuit which holds data and a plurality of comparison circuits which compare the data stored in the memory circuit (also referred to as storage data or data Dm) with search data (also referred to as data Dsch) (e.g., Patent Document 1).
In Patent Document 1, the memory circuit is an SRAM (static random access memory).